Semiconductor device

ABSTRACT

After the formation of a first interlayer insulating, an etching stopper film made of SiON is formed thereon. Subsequently, a contact hole extending from the upper surface of the etching stopper film and reaching a high concentration impurity region is formed, and a first plug is formed by filling W into the contact hole. Next, a ferroelectric capacitor, a second interlayer insulating film, and the like are formed. Thereafter, a contact hole extending from the upper surface of the interlayer insulating film and reaching the first plug is formed. Then, the contact hole is filled with W to form a second plug. With this, even when misalignment occurs, the interlayer insulating film is prevented from being etched.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of prior International PatentApplication No. PCT/JP2007/053138, filed Feb. 21, 2007, the entirecontents of which are incorporated herein by reference.

FIELD

The embodiments discussed herein are related to a semiconductor deviceincluding a ferroelectric capacitor configured by sandwiching aferroelectric film between a pair of electrodes and to a method formanufacturing the semiconductor device.

BACKGROUND

In recent years, development has been progressed for memories includinga ferroelectric capacitor which stores information using the hysteresischaracteristic of a ferroelectric material (Ferroelectric Random AccessMemory: hereinafter referred to as “FeRAM”). A FeRAM is a nonvolatilememory in which information is not erased even after power is turnedoff, and has excellent characteristics of achieving high integration,high speed driving, high durability, and low power consumption.

As a ferroelectric film material of a ferroelectric capacitor, mainlyused is a ferroelectric oxide having the perovskite crystal structuresuch as PZT (Pb(Zr,Ti)O₃) or SBT (SrBi₂Ta₂O₉) whose residualpolarization amount is large. The residual polarization amounts of theseferroelectric oxides are approximately 10 to 30 μC/cm².

FIG. 1 is a schematic view depicting an example of a semiconductordevice having a conventional ferroelectric capacitor. A semiconductorsubstrate 10 is separated into multiple element regions by an elementisolation film 11. A transistor T and other elements, which constitutean electronic circuit, are formed in each element region.

The transistor T includes a pair of high concentration impurity regions(source/drain) 18 each of which is formed by selectively injecting animpurity into the semiconductor substrate 10, a gate insulating film(unillustrated) formed on a region between the pair of these highconcentration impurity regions 18, and a gate electrode 14 formed on thegate insulating film. A stopper layer 20 is formed on the semiconductorsubstrate 10. This stopper layer 20 covers the transistor T and theelement isolation film 11. In addition, a first interlayer insulatingfilm 21 is formed on the stopper layer 20. A W (tungsten) plug 22 isformed in this interlayer insulating film 21, and the W plug 22 reachesone of the high concentration impurity regions 18 of the transistor Tfrom the upper surface of the interlayer insulating film 21.

A ferroelectric capacitor 30 is formed on the interlayer insulating film21, and has a structure in which a lower electrode 26 a, a ferroelectricfilm 27, and an upper electrode 28 a are stacked in this order from thebottom. This ferroelectric capacitor 30 is covered with a secondinterlayer insulating film 31 formed on the first interlayer insulatingfilm 21.

Wirings 37 of a first wiring layer are formed on the second interlayerinsulating film 31. One of these wirings 37 is electrically connected tothe upper electrode 28 a through a W plug 33 a extending from the uppersurface of the interlayer insulating film 31 and being connected to theupper electrode 28 a of the ferroelectric capacitor 30. Another wiring37 is electrically connected to the lower electrode 26 a through a Wplug 33 b extending from the upper surface of the interlayer insulatingfilm 31 and being connected to the lower electrode 26 a of theferroelectric capacitor 30. Still another wiring 37 is electricallyconnected to the W plug 22 through the W plug 33 c penetrating theinterlayer insulating film 31 in a vertical direction.

A third interlayer insulating film 40 is formed on the wirings 37 of thefirst wiring layer and the second interlayer insulating film 31. Wirings42 of a second wiring layer are formed on this third interlayerinsulating film 40. Some predetermined ones of these wirings 42 are eachelectrically connected to the wirings 37 of the first wiring layerthrough a W plug 41 penetrating the interlayer insulating film 40 in thevertical direction.

A fourth interlayer insulating film 46 is formed on the wirings 42 ofthe second wiring layer and the third interlayer insulating film 40.Wirings 48 of a third wiring layer and a terminal 49 are formed on thisfourth interlayer insulating film 46. A predetermined one of the wirings48 of the third wiring layer is electrically connected to the wiring 42of the second wiring layer through a W plug 47 penetrating theinterlayer insulating film 46 in the vertical direction.

On the wirings 48 of the third wiring layer and the fourth interlayerinsulating film 46, a first passivation film 51, a second passivationfilm 52, and a protection film 53 are formed in this order from thebottom. Then, the first passivation film 51, the second passivation film52, and the protection film 53, which are formed on the terminal 49, areselectively removed to expose the surface of the terminal 49.

As depicted in this FIG. 1, conventionally, the high concentrationimpurity region 18 of the transistor T and the wiring 37 of the firstwiring layer are connected to each other through the two W plugs 22 and33 c, which are lined up in the vertical direction. This configurationis employed because: the two interlayer insulating films 21 and 31 arepresent between the wiring 37 of the first wiring layer and the highconcentration impurity region 18; the wiring 37 of the first wiringlayer and the high concentration impurity region 18 has such a longdistance therebetween; so that long-time etching needs to be performedto form a contact hole extending from the upper surface of theinterlayer insulating film 31 and reaching the high concentrationimpurity region 18; and such long-time etching may badly damage theferroelectric capacitor 30. In short, with the long etching time,characteristic of the ferroelectric capacitor 30 deteriorates byreceiving plasma damages. In addition, if contact holes respectivelyreaching the upper electrode 28 a and the lower electrode 26 a and acontact hole reaching the high concentration impurity region 18 areformed simultaneously, the upper electrode 28 a and the lower electrode26 a are etched before the contact hole reaching the high concentrationimpurity region 18 is completed. Instead, the contact hole reaching thehigh concentration impurity region 18 may be formed alone. In this case,however, a problem arises that an etching amount is not stabilized(controlled etching is difficult) because of a high aspect ratio (anetching depth is too large relative to the diameter of the contacthole).

As depicted in FIG. 1, the two W plugs 22 and 33 c, which are formedindividually, connect the wiring 37 of the first wiring layer and thehigh concentration impurity region 18, whereby a damage given to theferroelectric capacitor 30 during the etching of the interlayerinsulating films can be suppressed. Thus, preferable ferroelectriccharacteristic can be obtained.

In this case, as depicted in FIG. 1, the size (diameter) of the W plug22 on a lower side is designed to be slightly larger than the size(diameter) of the W plug 33 c on an upper side. This design is made tosecurely form a contact hole right above the W plug 22 even if slightmisalignment occurs when a contact hole reaching the W plug 22 is formedfrom the upper surface of the interlayer insulating film 31 by thephotolithography method. In this way, the interlayer insulating film 21can be prevented from being etched when the contact hole is formed inthe interlayer insulating film 31.

Note that patent documents 1 to 4 disclose prior arts which areconsidered relevant to the embodiments discussed herein. Patent document1 discloses a semiconductor device in which: a silicide pad having ashape larger than that of a plug formed of polysilicon (polysiliconplug) is formed on top of the polysilicon plug; and a plug in an upperlayer and the polysilicon plug are electrically connected each otherthrough the silicide pad.

Patent document 2 discloses a semiconductor device manufacturing methodinvolving: sequentially forming a first conductive film and a secondconductive film on the entire upper surface of a substrate after forminga plug; patterning the second conductive film in a predetermined shape;performing isotropic etching of the first conductive film by using thesecond conductive film as a mask, thereby to form a connection pad, madeof the first conductive film, on a predetermined plug. The plug and thesecond conductive film (wiring) are electrically connected each otherthrough the connection pad.

Patent document 3 discloses a structure in a semiconductor device havinga stack-type capacitor. In this structure, a contact hole between animpurity region on a substrate surface and an aluminum wiring is filledwith polysilicon. Patent document 4 discloses a method for forming acontact plug having a large upper diameter, by performing isotropicetching and anisotropic etching in combination.

As described above, in consideration of misalignment occurring in thephotolithography process, the size (diameter) of the plug 22 has beenconventionally designed to be slightly larger than the size (diameter)of the contact hole formed thereon. However, with further size reduction(high integration) of a semiconductor device, the position of thecontact hole 31 a has been sometimes misaligned with the position of theplug 22 as depicted in FIG. 2A.

When the position of the contact hole 31 a is misaligned with theposition of the plug 22 as described above, a portion, near the upperportion of the plug 22, of the interlayer insulating film 21 is etchedwhen the contact hole 31 a is formed, and thus a depression 21 a isgenerated. Usually, when the formation of the contact hole 31 a iscompleted, a barrier metal (glue layer) is formed on the entire surfaceto cover the wall surface of the contact hole 31 a. However, as depictedin FIG. 2B, in the portion where the depression 21 a is formed, thebarrier metal 33 g is not filled into the bottom of the depression 21 a.Accordingly, the depression 21 a is left unfilled.

When moisture or impurities accumulate(s) in this depression 21 a, themoisture or impurities diffuse(s) into the interlayer insulating films21 and 31 during a heat treatment process performed thereafter, andreaches the ferroelectric film 27. This causes serious deterioration ofthe characteristic of the ferroelectric capacitor 30. In addition, evenif a semiconductor device has no problems right after beingmanufactured, long term use of the semiconductor device may cause themoisture or impurities to diffuse into the interlayer insulating films21 and 31, and thereby lead to deterioration of the characteristics ofthe ferroelectric capacitor 30 or the transistor T.

The size of the plug 22 may be further increased in order to prevent thedepression 21 a from being generated. However, if so, a problem arisesthat the size reduction of a semiconductor device is disturbed.

-   Patent document 1: Japanese Laid-open Patent Publication No.    2001-210711-   Patent document 2: Japanese Laid-open Patent Publication No.    10-289950-   Patent document 3: Japanese Laid-open Patent Publication No.    05-243517-   Patent document 4: Japanese Laid-open Patent Publication No.    08-236476

SUMMARY

According to an aspect of the embodiments, a semiconductor deviceincludes a semiconductor substrate, a transistor formed in thesemiconductor substrate, a first insulating film formed on thesemiconductor substrate to cover the transistor, an etching stopper filmformed on the first insulating film, a first plug formed by filling aconductive material into a contact hole extending from an upper surfaceof the etching stopper film and reaching an impurity region constitutingthe transistor, a ferroelectric capacitor formed on the etching stopperfilm, a second insulating film formed on the etching stopper film tocover the ferroelectric capacitor, and a second plug formed by filling aconductive material into a contact hole extending from an upper surfaceof the second insulating film and reaching the first plug.

According to another aspect of the embodiments, a method formanufacturing the semiconductor device includes forming a transistor ina semiconductor substrate, forming a first insulating film on thesemiconductor substrate, the first insulating film covering thetransistor, forming an etching stopper film on the first insulatingfilm, forming a first contact hole extending from an upper surface ofthe etching stopper film and reaching an impurity region constitutingthe transistor, forming a first plug by filling a conductive materialinto the first contact hole, forming a ferroelectric capacitor on theetching stopper film, the ferroelectric capacitor including a lowerelectrode, a ferroelectric film, and an upper electrode, forming asecond insulating film on the etching stopper film, the secondinsulating film covering the ferroelectric capacitor, forming a secondcontact hole extending from an upper surface of the second insulatingfilm and reaching the first plug by an etching method, and forming asecond plug by filling a conductive material into the second contacthole.

According to a further aspect of the embodiments, a semiconductor deviceincludes a semiconductor substrate, a transistor formed in thesemiconductor substrate, a first insulating film formed on thesemiconductor substrate to cover the transistor, an etching stopper filmformed on the first insulating film, a second insulating film formed onthe etching stopper film, a first plug formed by filling a conductivematerial into a contact hole extending from an upper surface of thesecond insulating film and reaching an impurity region constituting thetransistor, a ferroelectric capacitor formed on the second insulatingfilm, a third insulating film formed on the second insulating film tocover the ferroelectric capacitor, and a second plug formed by filling aconductive material into a contact hole extending from an upper surfaceof the third insulating film and reaching the first plug.

According to a still further aspect of the embodiments, a method formanufacturing a semiconductor device includes forming a transistor in asemiconductor substrate, forming a first insulating film on thesemiconductor substrate, the first insulating film covering thetransistor, forming an etching stopper film on the first insulatingfilm, forming a second insulating film on the etching stopper film,forming a first contact hole extending from an upper surface of thesecond insulating film and reaching an impurity region constituting thetransistor, forming a first plug by filling a conductive material intothe first contact hole, forming a ferroelectric capacitor on the secondinsulating film, the ferroelectric capacitor including a lowerelectrode, a ferroelectric film, and an upper electrode, forming a thirdinsulating film on the second insulating film, the third insulating filmcovering the ferroelectric capacitor, forming a second contact holeextending from an upper surface of the third insulating film andreaching the first plug by an etching method, and forming a second plugby filling a conductive material into the second contact hole.

According to a yet still further aspect of the embodiments, asemiconductor device includes a semiconductor substrate, a transistorformed in the semiconductor substrate, a first insulating film formed onthe semiconductor substrate to cover the transistor, an etching stopperfilm formed on the first insulating film, a first contact hole extendingfrom an upper surface of the etching stopper film and reaching animpurity region of the transistor, a second insulating film formed onthe etching stopper film and having an opening in a position alignedwith the first contact hole, the opening having a diameter larger than adiameter of the contact hole, a first plug formed by filling aconductive material into the first contact hole and the opening, aferroelectric capacitor formed on the second insulating film, a thirdinsulating film formed on the second insulating film to cover theferroelectric capacitor, a second contact hole extending from an uppersurface of the third insulating film and reaching the first plug, and asecond plug formed by filling a conductive material into the secondcontact hole.

According to a yet still further aspect of the embodiments, a method formanufacturing a semiconductor device includes forming a transistor in asemiconductor substrate, forming a first insulating film on thesemiconductor substrate, the first insulating film covering thetransistor, forming an etching stopper film on the first insulatingfilm, forming a second insulating film on the etching stopper film,forming an opening in the second insulating film, the opening allowingthe etching stopper film to be exposed, forming a first contact holeinside the opening, the first contact hole extending from an uppersurface of the etching stopper film, reaching an impurity region of thetransistor, and having a diameter smaller than a diameter of theopening, forming a first plug by filling a conductive material into thefirst contact hole and the opening, forming a ferroelectric capacitor onthe second insulating film, the ferroelectric capacitor including alower electrode, a ferroelectric film, and an upper electrode, forming athird insulating film on the second insulating film, the thirdinsulating film covering the ferroelectric capacitor, forming a secondcontact hole by an etching method, the second contact hole extendingfrom an upper surface of the third insulating film and reaching thefirst plug, and forming a second plug by filling a conductive materialinto the second contact hole.

According to a yet still further aspect of the embodiments, a method formanufacturing a semiconductor device includes forming a transistor in asemiconductor substrate, forming a first insulating film on thesemiconductor substrate, the first insulating film covering thetransistor, forming an etching stopper film on the first insulatingfilm, forming a first contact hole extending from an upper surface ofthe etching stopper film and reaching an impurity region of thetransistor, forming a plug axis part by filling a conductive materialinto the first contact hole, forming a second insulating film on theetching stopper film, etching the second insulating film to form anopening in which the plug axis part is exposed and which has a diameterlarger than a diameter of the plug axis part, filling a conductivematerial into the opening to form a plug head part constituting,integrally with the plug axis part, a first plug, forming aferroelectric capacitor on the second insulating film, the ferroelectriccapacitor including a lower electrode, a ferroelectric film, and anupper electrode, forming a third insulating film on the secondinsulating film, the third insulating film covering the ferroelectriccapacitor, forming a second contact hole by an etching method, thesecond contact hole extending from an upper surface of the thirdinsulating film and reaching the first plug, and forming a second plugby filling a conductive material into the second contact hole.

According to a yet still further aspect of the embodiments, a method formanufacturing a semiconductor device includes forming a transistor in asemiconductor substrate, forming a first insulating film on thesemiconductor substrate, the first insulating film covering thetransistor, forming an etching stopper film on the first insulatingfilm, forming a first contact hole extending from an upper surface ofthe etching stopper film and reaching an impurity region of thetransistor, forming a plug axis part by filling a conductive materialinto the first contact hole, forming a conductive film on the etchingstopper film and the plug axis part, patterning the conductive film toform a plug head part constituting, integrally with the plug axis part,a first plug and having a diameter larger than a diameter of the plugaxis part, forming a second insulating film on an entire upper surfaceof the semiconductor substrate, polishing the second insulating film toexpose the first plug, forming a ferroelectric capacitor on the secondinsulating film, the ferroelectric capacitor including a lowerelectrode, a ferroelectric film, and an upper electrode, forming a thirdinsulating film on the second insulating film, the third insulating filmcovering the ferroelectric capacitor, forming a second contact hole byan etching method, the second contact hole extending from an uppersurface of the third insulating film and reaching the first plug, andforming a second plug by filling a conductive material into the secondcontact hole.

According to a yet still further aspect of the embodiments, asemiconductor device includes a semiconductor substrate, a transistorformed on the semiconductor substrate, a first insulating film formed onthe semiconductor substrate to cover the transistor, a ferroelectriccapacitor formed on the first insulating film, a second insulating filmformed on the first insulating film to cover the ferroelectriccapacitor, an etching stopper film formed on the second insulating film,a first contact hole extending from an upper surface of the etchingstopper film and reaching an impurity region of the transistor, a firstplug formed by filling a conductive material into the first contacthole, a third insulating film formed on the etching stopper film, asecond contact hole extending from an upper surface of the thirdinsulating film and reaching the first plug, and a second plug formed byfilling a conductive material into the second contact hole.

According to a yet still further aspect of the embodiments, a method formanufacturing a semiconductor device includes forming a transistor in asemiconductor substrate, forming a first insulating film on thesemiconductor substrate, the first insulating film covering thetransistor, forming a ferroelectric capacitor on the first insulatingfilm, the ferroelectric capacitor including a lower electrode, aferroelectric film, and an upper electrode, forming a second insulatingfilm on the first insulating film, the second insulating film coveringthe ferroelectric capacitor, forming an etching stopper film on thesecond insulating film, forming a first contact hole extending from anupper surface of the etching stopper film and reaching an impurityregion of the transistor, forming a first plug by filling a conductivematerial into the first contact hole, forming a third insulating film onthe etching stopper film, forming a second contact hole by an etchingmethod, the second contact hole extending from an upper surface of thethird insulating film and reaching the first plug, and forming a secondplug by filling a conductive material into the second contact hole.

According to a yet still further aspect of the embodiments, asemiconductor device includes a semiconductor substrate, a transistorformed in the semiconductor substrate, a first insulating film formed onthe semiconductor substrate to cover the transistor, a ferroelectriccapacitor formed on the first insulating film, a second insulating filmformed on the first insulating film to cover the ferroelectriccapacitor, an etching stopper film formed on the second insulating film,a third insulating film formed on the etching stopper film, a firstcontact hole extending from an upper surface of the third insulatingfilm and reaching an impurity region of the transistor, a first plugformed by filling a conductive material into the first contact hole, afourth insulating film formed on the third insulating film, a secondcontact hole extending from an upper surface of the fourth insulatingfilm and reaching the first plug, and a second plug formed by filling aconductive material into the second contact hole.

According to a yet still further aspect of the embodiments, a method formanufacturing a semiconductor device includes forming a transistor in asemiconductor substrate, forming a first insulating film on thesemiconductor substrate, the first insulating film covering thetransistor, forming a ferroelectric capacitor on the first insulatingfilm, the ferroelectric film including a lower electrode, aferroelectric film, and an upper electrode, forming a second insulatingfilm on the first insulating film, the second insulating film coveringthe ferroelectric capacitor, forming an etching stopper film on thesecond insulating film, forming a third insulating film on the etchingstopper film, forming a first contact hole extending from an uppersurface of the third insulating film and reaching an impurity region ofthe transistor, forming a first plug by filling a conductive materialinto the first contact hole, forming a fourth insulating film on thethird insulating film, forming a second contact hole by an etchingmethod, the second contact hole extending from an upper surface of thefourth insulating film and reaching the first plug, and forming a secondplug by filling a conductive material into the second contact hole.

According to a yet still further aspect of the embodiments, asemiconductor device includes a semiconductor substrate, a transistorformed in the semiconductor substrate, a first insulating film formed onthe semiconductor substrate to cover the transistor, a ferroelectriccapacitor formed on the first insulating film, a second insulating filmformed on the first insulating film to cover the ferroelectriccapacitor, an etching stopper film formed on the second insulating film,a first contact hole extending from an upper surface of the etchingstopper film and reaching an impurity region of the transistor, a thirdinsulating film formed on the etching stopper film and having an openingin a position aligned with the first contact hole, the opening having adiameter larger than a diameter of the first contact hole, a first plugformed by filling a conductive material into the first contact hole andthe opening, a fourth insulating film formed on the third insulatingfilm, a second contact hole extending from an upper surface of thefourth insulating film and reaching the first plug, and a second plugformed by filling a conductive material into the second contact hole.

According to a yet still further aspect of the embodiments, a method formanufacturing a semiconductor device includes forming a transistor in asemiconductor substrate, forming a first insulating film on thesemiconductor substrate, the first insulating film covering thetransistor, forming a ferroelectric capacitor on the first insulatingfilm, the ferroelectric film including a lower electrode, aferroelectric film, and an upper electrode, forming a second insulatingfilm on the first insulating film, the second insulating film coveringthe ferroelectric capacitor, forming an etching stopper film on thesecond insulating film, forming a third insulating film on the etchingstopper film, forming an opening in the third insulating film, theopening allowing the etching stopper film to be exposed, forming a firstcontact hole inside the opening, the first contact hole extending froman upper surface of the etching stopper film, reaching an impurityregion of the transistor and having a diameter smaller than a diameterof the opening, forming a first plug by filling a conductive materialinto the first contact hole and the opening, forming a fourth insulatingfilm on the third insulating film, forming a second contact hole by anetching method, the second contact hole extending from an upper surfaceof the fourth insulating film and reaching the first plug, and forming asecond plug by filling a conductive material into the second contacthole.

The object and advantages of the embodiments will be realized andattained by means of the elements and combinations particularly pointedout in the claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and arenot restrictive of the embodiments, as claimed.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view depicting an example of a semiconductordevice having a conventional ferroelectric capacitor.

FIGS. 2A and 2B are schematic views, depicting a problem of aconventional art.

FIG. 3 is a schematic view depicting the structure of a semiconductordevice according to a first embodiment.

FIGS. 4A to 4R are cross-sectional views depicting a method formanufacturing a semiconductor device according to the first embodiment.

FIG. 5 is a schematic view depicting the structure of a semiconductordevice according to a second embodiment.

FIG. 6 is a schematic view depicting the structure of a semiconductordevice according to a third embodiment.

FIG. 7 is a schematic view depicting the structure of a semiconductordevice according to a fourth embodiment.

FIGS. 8A to 8F are cross-sectional views depicting a first method formanufacturing a semiconductor device according to the fourth embodiment.

FIGS. 9A to 9F are cross-sectional views depicting a second method formanufacturing a semiconductor device according to the fourth embodiment.

FIGS. 10A to 10F are cross-sectional views depicting a third method formanufacturing a semiconductor device according to the fourth embodiment.

FIG. 11 is a schematic view depicting the structure of a semiconductordevice according to a fifth embodiment.

FIG. 12 is a schematic view depicting the structure of a semiconductordevice according to a sixth embodiment.

FIG. 13 is a schematic view depicting the structure of a semiconductordevice according to a modified example of the sixth embodiment.

FIG. 14 is a schematic view depicting the structure of a semiconductordevice according to a seventh embodiment.

FIG. 15 is a schematic view depicting the structure of a semiconductordevice according to a modified example of the seventh embodiment.

FIG. 16 is a schematic view depicting the structure of a semiconductordevice according to an eighth embodiment.

FIG. 17 is a schematic view depicting the structure of a semiconductordevice according to a modified example of the eighth embodiment.

FIG. 18 is a schematic view depicting the structure of a semiconductordevice according to a ninth embodiment.

FIG. 19 is a schematic view depicting the structure of a semiconductordevice according to a modified example of the ninth embodiment.

FIG. 20 is a schematic view depicting the structure of a semiconductordevice according to a tenth embodiment.

FIG. 21 is a schematic view depicting the structure of a semiconductordevice according to a modified example of the tenth embodiment.

FIG. 22 is a top view depicting an example in which a hydrogen barrierfilm, a moisture barrier film, and an etching stopper film are onlypartially disposed on a semiconductor substrate.

FIG. 23 is a top view depicting an example in which films such as ahydrogen barrier film, a moisture barrier film, an etching stopper filmare formed on the entire upper surface of a semiconductor substrate,and, thereafter, the films in a scribe region are removed by etching.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention will be described below byreferring to the accompanying drawings.

(First Embodiment)

FIG. 3 is a schematic view depicting the structure of a semiconductordevice according to a first embodiment. A semiconductor substrate 110 isseparated into multiple element regions by an element isolation film111. A transistor T and other elements, which constitute an electroniccircuit, are formed in each element region.

The transistor T includes a pair of high concentration impurity regions118, each of which is formed by selectively injecting an impurity intothe semiconductor substrate 110, a gate insulating film (unillustrated)formed on a region between the pair of these high concentration impurityregions 118, and a gate electrode 114 formed on the gate insulatingfilm. A stopper layer 120 is formed on the semiconductor substrate 110.This stopper layer 120 covers the transistor T and the element isolationfilm 111. In addition, a first interlayer insulating film 121 is formedon the stopper layer 120. The upper surface of this interlayerinsulating film 121 is subjected to a planarizing process. Formed onthis interlayer insulating film 121 is an etching stopper film 122 madeof SiON.

A plug 124 reaching one of the high concentration impurity regions 118of the transistor T from the upper surface of the etching stopper film122 is formed inside the interlayer insulating film 121. In addition, onthe etching stopper film 122, a SiON film 125, a TEOS (oxide silicon)film 126, a hydrogen barrier film 127 made of aluminum oxide (forexample, Al₂O₃) are formed in this order from the bottom.

Formed on the hydrogen barrier film 127 is a ferroelectric capacitor 131with the structure in which a lower electrode 128 a, a ferroelectricfilm 129, and an upper electrode 130 a are stacked in this order fromthe bottom. This ferroelectric capacitor 131 is covered with a secondinterlayer insulating film 132 formed on the hydrogen barrier film 127.

The surface of the second interlayer insulating film 132 is planarizedand wirings 138 of a first wiring layer are formed on this interlayerinsulating film 132 to be in predetermined patterns. One of thesewirings 138 is electrically connected to an upper electrode 129 athrough a contact hole, extending from the upper surface of theinterlayer insulating film 132 and reaching the upper electrode 129 a ofthe ferroelectric capacitor 131. Another one is electrically connectedto a lower electrode 128 a through a contact hole extending from theupper surface of the interlayer insulating film 132 and reaching thelower electrode 128 a of the ferroelectric capacitor 131. Still anotherone is electrically connected to the plug 124 and the high concentrationimpurity region 118 through a plug 134 penetrating the interlayerinsulating film 132 in the vertical direction.

A hydrogen barrier film 139 made of aluminum oxide (for example, Al₂O₃)is formed on the interlayer insulating film 132 and the wiring 138 ofthe first wiring layer. A third interlayer insulating film 140 is formedon the hydrogen barrier film 139. Multiple plugs 141 are formed insidethis interlayer insulating film 140. The multiple plugs 141 penetratethrough the interlayer insulating film 140 in the vertical direction tobe electrically connected to the wirings 138 of the first wiring layer.In addition, multiple wirings 142 of a second wiring layer are formed onthe interlayer insulating film 140. As depicted in FIG. 3, apredetermined wiring of these wirings 142 is electrically connected tothe wiring 138 of the first wiring layer through the plug 141.

On the third interlayer insulating film 140 and the wirings 142 of thesecond wiring layer, a fourth interlayer insulating film 143 is formed.Multiple plugs 144 (only one is depicted in FIG. 3) are formed insidethis fourth interlayer insulating film 143. The multiple plugs 144penetrate through the interlayer insulating film 143 in the verticaldirection to be electrically connected to the wirings 142 of the secondwiring layer. In addition, wirings 145 of a third wiring layer and aterminal 146 are formed on the interlayer insulating film 143. Apredetermined wiring of these wirings 145 of the third wiring layer iselectrically connected to the wiring 142 of the second wiring layerthrough the plug 144.

On the fourth interlayer insulating film 143 and the wirings 145 of thethird wiring layer, a first passivation film 147, a second passivationfilm 148, and a protection film 149 are stacked in this order from thebottom. After that, the first passivation film 147, the secondpassivation film 148, and the protection film 149, which are formed onthe terminal 146, are selectively removed to expose the surface of theterminal 146.

As described above, the semiconductor device of the present embodimentis characterized in that the etching stopper film 122 made of SiON isformed on the first interlayer insulating film 121, the plug 124 isformed from the upper surface of the etching stopper film 122 to thehigh concentration impurity region 118, and a connected portion of theplug 124 and the plug 134 is positioned on the same plane as the uppersurface of the etching stopper film 122.

The semiconductor device of the present embodiment has the connectedportion of the plug 124 and the plug 134 on the same plane as the uppersurface of the etching stopper film 122. Accordingly, when the plug 134is formed, in other words, when the contact hole continuing to the plug124 is formed in the interlayer insulating film 132, the interlayerinsulating film 121 is prevented from being etched.

Note that the hydrogen barrier films 127 and 139 are provided forpreventing moisture and hydrogen in the interlayer insulating film 121or the interlayer insulating film 140 from moving into the ferroelectriccapacitor 131 to deteriorate the characteristic of the ferroelectriccapacitor 131. In addition, as depicted in FIG. 3, forming the lowerelectrode 128 a on the hydrogen barrier film 127 made of aluminum oxide(Al₂O₃) also is effective in improving the orientation of the lowerelectrode 128 a as well as the orientation of the ferroelectric film 129to be formed thereon. In the present invention, these hydrogen barrierfilms 127 and 139 are not essential. However, providing the hydrogenbarrier films 127 and 139 as depicted in FIG. 3 is preferable in orderto maintain the characteristic of the ferroelectric capacitor 131 over along period of time.

FIGS. 4A to 4R are cross-sectional views depicting a method formanufacturing a semiconductor device according to the first embodimentin the order of processes. Note that, the following descriptionillustrates an example in which the embodiment is applied to themanufacture of a FeRAM having a planar-type ferroelectric capacitor. Inaddition, FIGS. 4A to 4R depict cross sections in a peripheral circuitforming region, a memory cell forming region, and a terminal formingregion. Furthermore, it is assumed in the following description that amemory cell consists of an n-type transistor.

Firstly, the process to form the structure depicted in FIG. 4A will bedescribed. An element isolation film 111 is formed in a predeterminedregion of a semiconductor substrate (silicon substrate) 110 by thewell-known LOCOS (Local Oxidation of Silicon) method, so that thiselement isolation film 111 separates the semiconductor substrate 110into multiple element regions. The element isolation film 111 may beformed by the well-known STI (Shallow Trench Isolation) method.

Subsequently, a p-type impurity such as boron (B) is introduced into ann-type transistor forming region (n-type transistor forming regions inthe memory cell forming region and the peripheral circuit formingregion; same goes for the following expression) in the semiconductorsubstrate 110 to form a p-well 112. In addition, an n-type impurity suchas phosphorus (P) is introduced into a p-type transistor forming region(a p-type transistor forming region in the peripheral circuit formingregion; same goes for the following expression) in the semiconductorsubstrate 110 to form an n-well (unillustrated).

Thereafter, the surfaces of the p-well 112 and the n-well(unillustrated) are thermally oxidized to form a gate insulating film(unillustrated). After that, a silicon film (a polysilicon film or anamorphous silicon film) is formed on the entire upper surface of thesemiconductor substrate 110 by the CVD (Chemical Vapor Deposition)method. This silicon film is patterned by the photolithography method toform a gate electrode (silicon wiring) 114.

Note that it is preferable that a gate electrode into which an n-typeimpurity is introduced be formed above the p-well 122 and a gateelectrode into which a p-type impurity is introduced be formed above then-well (unillustrated). In addition, as depicted in FIG. 4A, in thememory cell forming region, two gate electrodes 114 are disposed so asto be parallel to each other on a single p-well 112.

After that, using the gate electrode 114 as a mask, an n-type impuritysuch as phosphorus (P) or arsenic (As) is shallowly ion-implanted intothe p-well 112 in the n-type transistor forming region, so that ann-type low concentration impurity region 116 is formed. Similar to this,using the gate electrode 114 as a mask, a p-type impurity such as boron(B) is shallowly ion-implanted into the n-well (unillustrated) in thep-type transistor forming region, so that a p-type low concentrationimpurity region (unillustrated) is formed.

Subsequently, sidewalls 117 are formed on both sides of the gateelectrode 114. These sidewalls 117 are formed in the following manner.An insulating film made of SiO₂, SiN, or the like is formed on theentire upper surface of the semiconductor substrate 110 by the CVDmethod. Thereafter, the insulating film is etched back to form thesidewalls 117.

After that, using the gate electrode 114 and the sidewall 117 as masks,an n-type impurity such as phosphorus (P) or arsenic (As) ision-implanted into the p-well 112 in the n-type transistor formingregion, so that an n-type high concentration impurity region 118 isformed. Similar to this, using the gate electrode in the p-typetransistor forming region and the sidewall as masks, a p-type impuritysuch as boron (B) is ion-implanted into the n-well (unillustrated), sothat a p-type high concentration impurity region (unillustrated) isformed. In this manner, the transistor T having source/drain with theLDD (Lightly Doped Drain) structure is formed in each transistor formingregion.

Note that it is preferable to form a metal silicide layer made of amaterial such as cobalt silicide or titanium silicide, as a contactlayer on the surfaces of the gate electrode 114 and the n-type highconcentration impurity region 118.

Next, as the stopper layer 120, a SiON film, for example, is formed bythe plasma CVD method to be 200 nm in thickness on the entire uppersurface of the semiconductor substrate 110. In addition, as the firstinterlayer insulating film 121, a TEOS-NSG(Tetra-Ethyl-Ortho-Silicate-Nondoped Silicate Glass: SiO) film, forexample, is formed by the plasma CVD method to be 600 nm in thickness onthe stopper layer 120. After that, the interlayer insulating film 121 ispolished by approximately 200 nm using the CMP (Chemical MechanicalPolishing) method, and thus the surface thereof is planarized.

After that, an etching stopper film 122 made of SiON is formed by theCVD method to be 100 nm in thickness on the interlayer insulating film121. This etching stopper film 122 is formed in order to prevent thefirst interlayer insulating film 121 from being etched in the etchingprocess for forming contact holes in the second interlayer insulatingfilm 132, which will be described later. This etching stopper film 122only needs to be formed of an insulating material having a lower etchingrate than that of the TEOS-NSG film constituting the second interlayerinsulating film 132. For example, the etching stopper film 122 may beformed of SiN. In the present embodiment, the thickness of the etchingstopper film 122 is designed to be 20 nm to 150 nm.

The etching stopper film 122 may be formed of a metal oxide such asaluminum oxide (AlxOy), titanium oxide (TiOx), zirconium oxide (ZrOx),magnesium oxide (MgOx), or MgTiOx. If the etching stopper film 122 isformed of one of these metal oxides, the etching stopper film 122functions also as a hydrogen barrier film to prevent moisture andhydrogen contained in the interlayer insulating film 121 from diffusinginto an upper layer. As a result, the reliability of FeRAM can befurther improved. However, if the etching stopper film 122 is formed ofany one of the above-described metal oxides, it is preferable that thefilm thickness be equal to or less than 100 nm. When the thickness ofthe etching stopper film 122 made of a metal oxide exceeds 100 nm, it isdifficult to make a hole in the etching stopper film 122 when a W plug124 is formed in a later process.

Next, the process to form the structure depicted in FIG. 4B will bedescribed. After the etching stopper film 122 is formed in theabove-described process, a photoresist is applied onto the etchingstopper film 122, so that a photoresist film 123 is formed.Subsequently, this photoresist film 123 is exposed to light anddeveloped to form, in a predetermined position, an opening 123 a inwhich the etching stopper film 122 is exposed. After that, etching isperformed by using the photoresist film 123 as a mask to form a contacthole 121 a extending from the upper surface of the etching stopper film122 and reaching the high concentration impurity region 118(source/drain of the transistor T). The diameter of this contact hole121 a is designed to be, for example, 0.55 μm.

Note that, in the present embodiment, as depicted in FIG. 4B, formed inthe peripheral circuit forming region are the contact hole 121 acontinuing to the high concentration impurity region 118 and the contacthole 121 a extending from the upper surface of the etching stopper film122 and reaching the gate electrode (silicon wiring) 114 on the elementisolation film 111.

Next, the process to form the structure depicted in FIG. 4C will bedescribed. After removing the photoresist film 123 used for forming thecontact holes 121 a, a Ti film with the thickness of 20 nm and a TiNfilm with the thickness of 50 nm (both of which are unillustrated) aresequentially formed by, for example, the PVD (Physical Vapor Deposition)method on the entire upper surface of the semiconductor substrate 110.As a result, the wall surface of the contact holes 121 a are coveredwith the Ti film and the TiN film. Thereafter, W (tungsten) is depositedby, for example, the CVD method on the entire upper surface of thesemiconductor substrate 110, so that a W film is formed on the etchingstopper film 122 and the contact holes 121 a are filled with W.

Next, the W film, the TiN film, and the Ti film which are on the etchingstopper film 122 are removed by the CMP method. In this manner, W plugs124 are formed by filling the contact holes 121 a with W. In this case,as depicted in FIG. 4C, the upper surfaces of the W plugs 124 and theupper surface of the etching stopper film 122 are positioned on the sameplane.

Thereafter, plasma annealing is performed in an atmosphere containingnitrogen and oxygen at the temperature of 350° C. for 2 minutes. Then,by the plasma CVD method, a SiON film 125 is formed on the entire uppersurface of the semiconductor substrate 110 to be 100 nm in thickness toprevent the W plug 124 from being oxidized. Note that a SiON film formedby the plasma CVD method generally has a characteristic of being hardlypermeable to moisture, and, thus, the SiON film 125 also functions as amoisture barrier layer to prevent moisture from moving in the verticaldirection.

Next, the process to form the structure depicted in FIG. 4D will bedescribed. After the moisture barrier film 125 is formed in theabove-described process, a TEOS (silicon oxide) film 126 is formed bythe CVD method to be 100 nm in thickness on the SiON film 125.Subsequently, as a dewatering process, a heat treatment is performed inan atmosphere with the flow rate of nitrogen being 2 litters per minuteat the temperature of 650° C. for 30 minutes. Thereafter, for example bythe CVD method, aluminum oxide (for example, Al₂O₃) is deposited on theTEOS film 126 to be 20 nm in thickness, so that a hydrogen barrier film127 is formed. After that, a heat treatment (RTA process) is performedin an atmosphere with the flow rate of oxygen being 2 litters per minutefor 60 seconds.

Next, the process to form the structure depicted in FIG. 4E will bedescribed. After the hydrogen barrier film 127 is formed in theabove-described process, a conductive film 128 serving as a lowerelectrode of a ferroelectric capacitor is formed on the hydrogen barrierfilm 127. This conductive film 128 is formed of, for example, a metal,such as Pt (platinum), Ir (iridium), Ru (ruthenium), Rh (rhodium), Re(rhenium), Os (osmium), or Pd (palladium), or an oxide of one of thosemetals (conductive oxide). In the present embodiment, the conductivefilm 128 is designed to be formed by depositing Pt using the PVD methodto be 155 nm in thickness on the hydrogen barrier film 127.

Subsequently, a ferroelectric film 129 is formed on the conductive film128. The ferroelectric film 129 may be formed of PZT, PLZT, BLT, SBT, orthe like. In the present embodiment, the ferroelectric film 129 isdesigned to be formed by depositing PZT to be 150 to 200 nm in thicknesson the conductive film 128 using the PVD method.

After forming the ferroelectric film 129 as described above, the RTAprocess is performed in an atmosphere containing oxygen to crystallizethe ferroelectric film 129. In the present embodiment, an oxygen gas issupplied into the RTA device with the flow rate of 0.025 litters perminute and a heat treatment is performed at the temperature of, forexample, 565° C. for 90 seconds.

After that, a conductive film 130 serving as an upper electrode of theferroelectric capacitor is formed on the ferroelectric film 129. Theconductive film 130 is formed of, for example, a metal such as Pt, Ir,Ru, Rh, Re, Os, or Pd, or an oxide of one of these metals (conductiveoxide). In the present embodiment, a first IrO₂ film is formed bydepositing IrO₂ to be 50 nm in thickness on the ferroelectric film 129.After that, the semiconductor substrate 110 is placed inside the RTAdevice and the RTA process is performed under conditions of the supplyamount of oxygen gas being 0.025 litters per minute, the temperature of725° C., and the processing time of 20 seconds. Thereafter, a secondIrO₂ film is formed by depositing IrO₂ to be 200 nm in thickness on thefirst IrO₂ film using the PVD method. In this manner, formed is theconductive film 130 with the structure in which the first and secondIrO₂ films are stacked.

Next, the process to form the structure depicted in FIG. 4F will bedescribed. After the conductive film 130 is formed in theabove-described process, a resist film (unillustrated) covering an upperelectrode forming region of the ferroelectric capacitor is formed by thephotolithography method. After that, the conductive film 130 is etchedby using the resist film as a mask to form an upper electrode 130 a.Subsequently, the resist film on the upper electrode 130 a is removed.

Thereafter, recovery annealing for the ferroelectric film 129 isperformed. That is, the semiconductor substrate 110 is placed inside aheating furnace and a heat treatment is performed under conditions ofthe supply amount of oxygen being 20 litters per minute, the temperatureof 650° C., and the processing time of 60 minutes.

After performing the recovery annealing for the ferroelectric film 129,a resist film (unillustrated) covering above a ferroelectric capacitorforming region is formed by the photolithography method. Then, theferroelectric film 129 is etched by using the resist film as a mask toform the ferroelectric film 129 in a predetermined shape. After that,the resist film is removed.

Thereafter, the semiconductor substrate 110 is placed inside the heatingfurnace to perform the recovery annealing for the ferroelectric film129. This recovery annealing is performed under conditions of, forexample, the supply amount of oxygen into the heating furnace being 20litters per minute, the temperature of 350° C., and the processing timeof 60 minutes.

Next, the process to form the structure depicted in FIG. 4G will bedescribed. After the ferroelectric film 129 is patterned in theabove-described process, a resist film (unillustrated) covering above alower electrode forming region of the ferroelectric capacitor is formedby the photolithography method. Then, the conductive film 128 is etchedby using this resist film as a mask to form a lower electrode 128 a.After that, the resist film is removed.

Thereafter, the semiconductor substrate 110 is placed inside the heatingfurnace to perform the recovery annealing for the ferroelectric film129. This recovery annealing is performed under conditions of, forexample, the supply amount of oxygen into the heating furnace being 20litters per minute, the temperature of 650° C., and the processing timeof 60 minutes. In this manner, a ferroelectric capacitor 131 iscompleted.

Next, an interlayer insulating film 132 is formed by depositing TEOS-NSGto be 1500 nm in thickness on the entire upper surface of thesemiconductor substrate 110 using, for example, the plasma CVD method.This interlayer insulating film 132 covers the ferroelectric capacitor131. After that, the upper surface of the interlayer insulating film 132is planarized by the CMP method.

Note that, though unillustrated in FIG. 4G, it is preferable that ahydrogen barrier film (aluminum oxide film) be formed by the PVD methodto be, for example, 20 nm in thickness on the entire upper surface ofthe substrate 110 after the ferroelectric capacitor 131 is formed. Withthis, the entrance of moisture and hydrogen into the ferroelectriccapacitor 131 can be further securely prevented. If this hydrogenbarrier film is formed, a heat treatment is performed in an atmospherecontaining oxygen at the temperature of 550° C. for 60 minutes. Similarto this, in other embodiments of the present application, it is alsopreferable that a hydrogen barrier film be formed on the entire uppersurface of a semiconductor substrate after a ferroelectric capacitor isformed.

Next, the process to form the structure depicted in FIG. 4H will bedescribed. After the surface of the interlayer insulating film 132 isplanarized in the above-described process, plasma annealing is performedin an atmosphere containing, for example, nitrogen and oxygen at thetemperature of 350° C. for 2 minutes to nitride the surface of theinterlayer insulating film 132. After that, a photoresist is appliedonto the interlayer insulating film 132 to form a photoresist film 133.Then, this photoresist film 133 is exposed to light and developed toform an opening 133 a in a predetermined position. After that, theetching process is performed by using this photoresist film 133 as amask, so that a contact hole 132 a extending from the upper surface ofthe interlayer insulating film 132 and reaching the W plug 124 isformed. It is preferable that the diameter of this contact hole 132 a beslightly smaller than the diameter of the contact hole 121 a (0.55 μm)when the W plug 124 is formed. In the present embodiment, the diameterof the contact hole 132 a is designed to be 0.5 μm.

Even when misalignment occurs when this contact hole 132 a is formed,the interlayer insulating film 121 is prevented from being etchedbecause the etching stopper film 122 is formed around the W plug 124. Asa result, problems are solved in that the interlayer insulating film isetched to generate a depression and that moisture or impurities, whichaccumulate(s) in the depression, deteriorates the characteristic of theferroelectric capacitor (see, for example, FIG. 2).

Next, the process to form the structure depicted in FIG. 4I will bedescribed. After removing the photoresist film 133 used for forming thecontact hole 132 a, a Ti film with the thickness of 20 nm and a TiN filmwith the thickness of 50 nm (both of which are unillustrated) aresequentially formed by, for example, the PVD method on the entire uppersurface of the semiconductor substrate 110. Then, the wall surface ofthe contact hole 132 a is covered with these Ti film and TiN film.Thereafter, W (tungsten) is deposited by, for example, the CVD method onthe entire upper surface of the semiconductor substrate 110, so that a Wfilm is formed on the interlayer insulating film 132 and the contacthole 132 a is filled with W.

After that, the W film, the TiN film, and the Ti film which are on theinterlayer insulating film 132 are removed by the CMP method. In thismanner, a W plug 134 is formed by filling the contact hole 132 a with W.Subsequently, plasma annealing is performed in an atmosphere containing,for example, nitrogen and oxygen at the temperature of 350° C. for 2minutes to nitride the surface of the interlayer insulating film 132.After that a SiON film 135 is formed by the CVD method to be 100 nm inthickness on the interlayer insulating film 132 to prevent the W plug134 from being oxidized.

Next, the processes to form the structures depicted in FIG. 4J, FIG. 4K,and FIG. 4L will be described. After the SiON film 135 is formed in theabove-described process, as depicted in FIG. 4J, a photoresist isapplied onto the SiON film 135 to form a photoresist film 136. Then,this photoresist film 136 is exposed to light and developed to form anopening in a predetermined position. After that, the etching process isperformed by using this photoresist film 136 as a mask to form a contacthole 132 b extending from the upper surface of the SiON film 135 andreaching the upper electrode 130 a of the ferroelectric capacitor 131and a contact hole 132 b extending from the upper surface of the SiONfilm 135 and reaching the lower electrode 128 a of the ferroelectriccapacitor 131. Subsequently, after removing the photoresist film 136,recovery annealing for the ferroelectric film 129 is performed. Thisrecovery annealing is performed by heating in, for example, an oxygenatmosphere at the temperature of 500° C. for 60 minutes.

Next, as depicted in FIG. 4K, the SiON film 135 is removed by etching.Subsequently, as depicted in FIG. 4L, TiN with the thickness of 150 nm,Al—Cu alloy with the thickness of 550 nm, Ti with the thickness of 5 nm,and TiN with the thickness of 150 nm are deposited in this order on theentire upper surface of the semiconductor substrate 110 by, for example,the PVD method, so that an aluminum film 137 is formed on the interlayerinsulating film 132 and the contact holes 132 b are filled withaluminum.

Next, the process to form the structure depicted in FIG. 4M will bedescribed. After the aluminum film 137 is formed in the above-describedprocess, the aluminum film 137 is patterned by using thephotolithography method and the etching method, so that a wiring 138 ofa first wiring layer is formed. In the present embodiment, the upperelectrode 130 a of the ferroelectric capacitor 131 is electricallyconnected to the high concentration impurity region 118 of thetransistor T through the wiring 138, the W plug 134, and the W plug 124.In this manner, the wiring 138 of the first wiring layer is formed.Thereafter, a heat treatment is performed under conditions of, forexample, the supply amount of nitrogen being 20 litters per minute, thetemperature of 350° C., and the processing time of 30 minutes.Thereafter, an aluminum oxide (for example, Al₂O₃) film as the hydrogenbarrier film 139 is formed by the PVD method to be 20 nm in thickness onthe entire upper surface of the semiconductor substrate 110.

Next, the processes to form the structures depicted in FIG. 4N and FIG.4O will be described. After the hydrogen barrier film 139 is formed inthe above-described process, TEOS-NSG is deposited by, for example, theplasma CVD method with a thickness of approximately 2600 nm, so that aninterlayer insulating film 140 is formed as depicted in FIG. 4N.Thereafter, the surface of the interlayer insulating film 140 ispolished by the CMP method, and thus planarized. Subsequently, thephotolithography method and the etching method are used to form acontact hole extending from the upper surface of the interlayerinsulating film 140 and reaching the wiring 138 of the first wiringlayer. Then, a Ti film with the thickness of 20 nm and a TiN film withthe thickness of 50 nm are formed on the entire upper surface of thesemiconductor substrate 110. After that, W (tungsten) is deposited bythe CVD method on the entire upper surface of the semiconductorsubstrate 110, so that the contact hole is filled with W. Thereafter,the CMP polishing is performed until the interlayer insulating film 140is exposed to form a W plug 141.

Next, by a method similar to the method for forming the wiring of thefirst wiring layer, an aluminum film is formed on the entire uppersurface of the semiconductor substrate 110. Then, this aluminum film ispatterned to form wirings 142 of a second wiring layer as depicted inFIG. 4O. As depicted in this FIG. 4O, a predetermined wiring of thewirings 142 of the second wiring layer is electrically connected to thetransistor T (high concentration impurity layer 118) through the W plug141, the wiring 138 of the first wiring layer, the W plug 134, and the Wplug 124.

Next, the process to form the structure depicted in FIG. 4P will bedescribed. After the wiring 142 of the second wiring layer is formed inthe above-described process, TEOS-NSG is deposited by, for example, theplasma CVD method to be approximately 2200 nm in thickness to form aninterlayer insulating film 143 covering the wiring 142 of the secondwiring layer. Thereafter, the surface of the interlayer insulating film143 is planarized by the CMP method. Subsequently, the photolithographymethod and the etching method are used to form a contact hole extendingfrom the upper surface of the interlayer insulating film 143 andreaching the wiring 142 of the second wiring layer and W (tungsten) isfilled into the contact hole to form a W plug 144. After that, analuminum film is formed on the entire upper surface of the semiconductorsubstrate 110. Then, this aluminum film is patterned to form a wiring145 of a third wiring layer and a terminal 146.

Next, the process to form the structure depicted in FIG. 4Q will bedescribed. After the wiring 145 of the third wiring layer and theterminal 146 are formed in the above-described process, TEOS-NSG isdeposited by the plasma CVD method to be approximately 100 nm inthickness on the entire upper surface of the semiconductor substrate110, so that a first passivation film 147 covering the wiring 145 andthe terminal 146 is formed. Then, plasma annealing is performed on thefirst passivation film 147 in a nitrogen atmosphere. The temperature inthe annealing is designed to be, for example, 350° C. and the processingtime is designed to be, for example, 2 minutes.

Thereafter, SiN is deposited by, for example, the plasma CVD method tobe 350 nm in thickness on the first passivation film 147, so that asecond passivation film 148 is formed.

Next, the process to form the structure depicted in FIG. 4R will bedescribed. After the first and second passivation films 147 and 148 areformed in the above-described process, the first and second passivationfilms 147 and 148 on the terminal 146 are removed by using thephotolithography method and the etching method. After that,photosensitive polyimide is applied onto the entire upper surface of thesemiconductor substrate 110 to be approximately 3.6 μm in thickness, sothat a protection film 149 is formed. Then, the protection film 149 isexposed to light and developed to form an opening 149 a in which theterminal 146 is exposed. Subsequently, a heat treatment is performed in,for example, a nitrogen atmosphere at the temperature of 310° C. for 40minutes to cure polyimide constituting the protection film 149. In thismanner, a semiconductor device (FeRAM) according to the presentembodiment is completed. Note that the protective film 149 may be formedof nonphotosensitive polyimide.

In the present embodiment, as depicted in FIG. 4H, the etching stopperfilm 122 is formed on the first interlayer insulating film 121.Accordingly, even when misalignment occurs when the contact hole 132 acontinuing to the plug 124 is formed in the second interlayer insulatingfilm 132, the first interlayer insulating film 121 is not etched. Thus,a depression 21 a as depicted in FIG. 2 is not generated. Accordingly,the deterioration of the characteristic caused by moisture or impuritieswhich accumulate(s) in the depression 21 a is prevented. Thus, thereliability of the semiconductor device (FeRAM) can be ensured over along period.

In addition, in the present invention, the hydrogen barrier films 127and 139 are formed below and above the ferroelectric capacitor 131.Accordingly, the entrance of moisture and hydrogen into theferroelectric capacitor 131 can be more securely prevented. With this,the deterioration of the characteristic of the ferroelectric capacitor131 can be suppressed, so that the reliability of the semiconductordevice can be further improved.

(Second Embodiment)

FIG. 5 is a schematic view depicting the structure of a semiconductordevice according to a second embodiment. The present embodiment isdifferent from the first embodiment in that a TEOS (silicon oxide) film211 is formed on an etching stopper film 122, a connected portion of aplug 124 and a plug 134 is positioned on the same plane as the uppersurface of the TEOS film 211, and between a wiring 138 of a first wiringlayer and an upper electrode 130 a of a ferroelectric capacitor 131 andbetween the wiring 138 of the first wiring layer and a lower electrode128 a of the ferroelectric capacitor 131 are respectively connected by Wplugs 212. Other components are basically the same as those of the firstembodiment. Accordingly, in FIG. 5, the same reference numerals aregiven to denote the components same as those in FIG. 3, and thedescription of the same components is omitted.

In the present embodiment, after an etching stopper film 122 is formed,a TEOS film 211 is formed by the CVD method to be 50 to 100 nm inthickness on the etching stopper film 122. Subsequently, thephotolithography method and the etching method are used to form acontact hole extending from the upper surface of the TEOS film 211 andreaching a high concentration impurity region 118. Then, this contacthole is filled with W (tungsten), so that a W plug 124 is formed. Afterthat, similar to the first embodiment, a SiON film 125, a TEOS film 126,and a hydrogen barrier film 127 are formed. Furthermore, a ferroelectriccapacitor 131 and an interlayer insulating film 132 are formed.

Next, a photoresist film is formed on the interlayer insulating film132, and is exposed to light and developed, so that an opening is formedin the photoresist film in a portion above the plug 124. Then, theetching is performed by using this photoresist film as a mask to form acontact hole extending from the upper surface of the interlayerinsulating film 132 and reaching the plug 124. Subsequently, thephotoresist film is removed, and, thereafter, the contact hole is filledwith W (tungsten) to form a W plug 134 to be electrically connected tothe W plug 124.

Note that the TEOS film 211 could be etched due to misalignment occurredwhen the contact hole is formed. However, the thickness of the TEOS film211 is 50 to 100 nm, which is extremely thin, and the etching stopperfilm 122 is also formed thereunder. Accordingly, the occurrence of alarge depression as depicted in FIG. 2 is prevented.

Next, a SiON film (unillustrated) is formed on the entire upper surfaceof the semiconductor substrate 110. Subsequently, a photoresist film isformed on this SiON film and is exposed to light and developed, so thatopenings are formed in the photoresist film in portions above the upperelectrode 130 a and lower electrode 128 a of the ferroelectric capacitor131. After that, the etching process is performed by using thephotoresist film as a mask to form a contact hole extending from theupper surface of the interlayer insulating film 132 and reaching theupper electrode 130 a of the ferroelectric capacitor 131 and a contacthole extending from the upper surface of interlayer insulating film 132and reaching the lower electrode 128 a of the ferroelectric capacitor131. Then, the photoresist film and the SiON film are removed, and,thereafter, the contact holes are filled with W (tungsten), so that Wplugs 212, which are respectively connected to the upper electrode 130 aand lower electrode 128 a of the ferroelectric capacitor 131, areformed.

The processes thereafter are the same as those of the first embodiment,and the description thereof is omitted here. In the present embodimentas well, effects similar to those of the first embodiment can beobtained.

(Third Embodiment)

FIG. 6 is a schematic view depicting the structure of a semiconductordevice according to a third embodiment. The present embodiment isdifferent from the first embodiment in that a SiON film 221 is formed onan etching stopper film 122, a connected portion of a plug 124 and aplug 134 is positioned on the same plane as the upper surface of theSiON film 221, and between a wiring 138 of a first wiring layer and anupper electrode 130 a of a ferroelectric capacitor 131 and between thewiring 138 of the first wiring layer and a lower electrode 128 a of theferroelectric capacitor 131 are respectively connected by W plugs 212.Other components are basically the same as those of the firstembodiment. Accordingly, in FIG. 6, the same reference numerals aregiven to denote the components same as those in FIG. 3, and thedescription of the same components is omitted.

In the present embodiment, after an etching stopper film 122 is formed,a SiON film 221 is formed by the CVD method to be 50 to 100 nm inthickness on the etching stopper film 122. Subsequently, thephotolithography method and the etching method are used to form acontact hole extending from the upper surface of the SiON film 221 andreaching a high concentration impurity region 118. Then, this contacthole is filled with W (tungsten) to form a W plug 124. After that,similar to the first embodiment, a SiON film 125, a TEOS film 126, and ahydrogen barrier film 127 are formed, and a ferroelectric capacitor 131and an interlayer insulating film 132 are formed.

Next, a photoresist film is formed on the interlayer insulating film132, and is exposed to light and developed, so that an opening is formedin the photoresist film in a portion above the plug 124. Subsequently,the etching is performed by using this photoresist film as a mask toform a contact hole extending from the upper surface of the interlayerinsulating film 132 and reaching the plug 124. After that, thephotoresist film is removed, and, thereafter, the contact hole is filledwith W (tungsten) to form a W plug 134, which is electrically connectedto the plug 124.

Thereafter, a SiON film (unillustrated) is formed on the entire uppersurface of the semiconductor substrate 110. Subsequently, a photoresistfilm is formed on this SiON film and is exposed to light and developed,so that openings are formed in the photoresist film in portions abovethe upper electrode 130 a and lower electrode 128 a of the ferroelectriccapacitor 131. After that, the etching is performed by using thephotoresist film as a mask to form a contact hole extending from theupper surface of the interlayer insulating film 132 and reaching theupper electrode 130 a of the ferroelectric capacitor 131, and a contacthole extending from the upper surface of the interlayer insulating film132 and reaching the lower electrode 128 a of the ferroelectriccapacitor 131. Then, the photoresist film and the SiON film are removed.Thereafter, the contact holes are filled with W (tungsten), so that Wplugs 212, which are respectively connected to the upper electrode 130 aand lower electrode 128 a of the ferroelectric capacitor 131, areformed.

The processes thereafter are the same as those of the first embodiment,and the description thereof is omitted here. In the present embodiment,effects similar to those of the first embodiment can be also obtained.

(Fourth Embodiment)

FIG. 7 is a schematic view depicting the structure of a semiconductordevice according to a fourth embodiment. The present embodiment isdifferent from the first embodiment in the shape of the upper portion ofa plug which is to be electrically connected to a high concentrationimpurity region 118 of a transistor T. Other components are basicallythe same as those of the first embodiment. Accordingly, in FIG. 7, thesame reference numerals are given to denote the components same as thosein FIG. 3.

In the present embodiment, as depicted in FIG. 7, a TEOS (silicon oxide)film 242 is formed on an etching stopper film 122, and a SiON film 125,a TEOS film 126, and a hydrogen barrier film 127 are formed thereon. Aplug 241 is formed by filling W (tungsten) into the contact holeextending from the upper surface of the TEOS film 242 and reaching thehigh concentration impurity region 118 of the transistor T. The headportion of this plug 241 (a portion higher than the etching stopper film122) has the diameter larger than that of another portion (axisportion). For example, the diameter of the axis portion is 0.55 μm andthe diameter of the head portion is 0.7 μm.

In the present embodiment, effects similar to those of the firstembodiment can be obtained. In addition, since the diameter of the headportion of the plug 241 is largely formed, even when misalignment occursbetween the plug 241 and the plug 134 to be formed thereon, theelectrical connection between the plugs 241 and 134 can be preferablymaintained.

Three methods for manufacturing a semiconductor device according to thepresent embodiment will be described below. Note that, in the followingdescription, the description will be given of an example in which thepresent invention is applied to a FeRAM having a planar-typeferroelectric capacitor.

(First Manufacturing Method)

FIG. 8A to FIG. 8F are cross-sectional views depicting a first methodfor manufacturing a semiconductor device according to the presentembodiment in the order of processes.

Firstly, by a method similar to that of the first embodiment, asdepicted in FIG. 8A, formed on and in a semiconductor substrate 110 arean element isolation film 111, a p-well 112, a gate electrode 114, a lowconcentration impurity region 116, a sidewall 117, a high concentrationimpurity region 118, a stopper layer 120, and a first interlayerinsulating film 121. Thereafter, a SiON film as an etching stopper film122 is formed by the CVD method to be 100 nm in thickness on theinterlayer insulating film 121. Furthermore, a TEOS film 242 is formedthereon by the CVD method to be 100 nm in thickness.

Next, as depicted in FIG. 8B, a photoresist is applied onto the TEOSfilm 242 to form a photoresist film 243. Then, this photoresist film 243is exposed to light and developed to form an opening 243 a in apredetermined region. After that, the TEOS film 242 is etched by usingthe photoresist film 243 as a mask to form an opening 242 a.

Next, after the photoresist film 243 is removed, as depicted in FIG. 8C,a photoresist is applied onto the entire upper surface of thesemiconductor substrate 110 to form a photoresist film 244. Then, thisphotoresist film 244 is exposed to light and developed to form anopening 244 a. This opening 244 a is formed in a position aligned withthe opening 242 a in the TEOS film 242 with a diameter slightly smallerthan that of the opening 242 a. In the present embodiment, the diameterof the opening 242 a is designed to be 0.7 μm and the diameter of theopening 244 a is designed to be 0.55 μm. Note that, here, since a basehas a stepped portion, it is better to form the photoresist film afteran antireflection film (BARC) is applied in order to precisely form apattern. Both approaches may be used.

Subsequently, as depicted in FIG. 8D, the etching is performed by usingthe photoresist film 244 as a mask to form a contact hole 121 aextending from the upper surface of the etching stopper film 122 andreaching the high concentration impurity region 118 (source/drain of thetransistor T). Here, not only the contact hole 121 a extending from theupper surface of the etching stopper film 122 and reaching the highconcentration impurity region 118, but also formed is the contact hole121 a extending from the upper surface of the etching stopper film 122and reaching the gate electrode (silicon wiring) 114 on the elementisolation film 111 in the peripheral circuit forming region.

Next, after the photoresist film 244 is removed, a Ti film with thethickness of 20 nm and a TiN film with the thickness of 50 nm (both ofwhich are unillustrated) are formed by, for example, the PVD method onthe entire upper surface of the semiconductor substrate 110. Then, thewall surface of the contact hole 121 a is covered with these Ti film andTiN film. Thereafter, W (tungsten) is deposited by, for example, the CVDmethod on the entire upper surface of the semiconductor substrate 110,so that a W film is formed on the TEOS film 242 and the contact hole 121a is filled with W. After that, the W film, the TiN film, and the Tifilm which are on the TEOS film 24 are removed by the CMP method. Withthis, as depicted in FIG. 8E, a W plug 241 is formed by filling thecontact hole 121 a with W. This W plug 241 has the shape (a rivet-likeshape) in which the diameter of the upper (head) portion thereof islarger than that of another portion (axis portion). After the CMPprocess, the plasma annealing is performed in an atmosphere containingnitrogen and oxygen at the temperature of 350° C. for 2 minutes.

Next, as depicted in FIG. 8F, a SiON film 125 is formed by the plasmaCVD method to be 100 nm in thickness on the entire upper surface of thesemiconductor substrate 110. Subsequently, a TEOS film 126 is formed bythe CVD method to be 100 nm in thickness on the SiON film 125. Then, thedewatering process is performed by heating under conditions of the flowrate of nitrogen being 2 litters per minute and the temperature of 650°C. for 30 minutes. Thereafter, a hydrogen barrier film 127 made ofaluminum oxide (for example, Al₂O₃) is formed by the PVD method on theTEOS film 126. The processes thereafter are the same as those of thefirst embodiment, and the description thereof is omitted here.

(Second Manufacturing Method)

FIGS. 9A to 9F are cross-sectional views depicting a second method formanufacturing a semiconductor device according to the present embodimentin the order of processes.

Firstly, by a method similar to that of the first embodiment, asdepicted in FIG. 9A, formed on and in a semiconductor substrate 110 arean element isolation film 111, a p-well 112, a gate electrode 114, a lowconcentration impurity region 116, a sidewall 117, a high concentrationimpurity region 118, a stopper layer 120, a first interlayer insulatingfilm 121, and the like. After that, a SiON film as an etching stopperfilm 122 is formed by the CVD method to be in thickness 100 nm on theinterlayer insulating film 121.

Subsequently, as depicted in FIG. 9B, a photoresist is applied onto theetching stopper film 122 to form a photoresist film 251. Then, thisphotoresist film 251 is exposed to light and developed to form anopening 251 a having the diameter of 0.55 μm in a predetermined region.After that, the etching is performed by using the photoresist film 251as a mask to form a contact hole 121 a extending from the upper surfaceof the etching stopper film 122 and reaching the high concentrationimpurity region 118. Here, formed are not only the contact hole 121 aextending from the upper surface of the etching stopper film 122 andreaching the high concentration impurity region 118 but also the contacthole 121 a extending from the upper surface of the etching stopper film122 and reaching the gate electrode (silicon wiring) 114 on the elementisolation film 111 in the peripheral circuit forming region.

Next, after the photoresist film 251 is removed, a Ti film with thethickness of 20 nm and a TiN film with the thickness of 50 nm (both ofwhich are unillustrated) are formed by, for example, the PVD method onthe entire upper surface of the semiconductor substrate 110. Then, thewall surface of the contact hole 121 a is covered with these Ti film andTiN film. Thereafter, W (tungsten) is deposited by, for example, the CVDmethod on the entire upper surface of the semiconductor substrate 110,so that a W film is formed on the etching stopper film 122 and thecontact hole 121 a is filled with W. After that, the W film, the TiNfilm, and the Ti film which are on the etching stopper film 122 areremoved by the CMP method. With this, as depicted in FIG. 9C, a W plug241 (however, the head portion is excluded) is formed by filling thecontact hole 121 a with W.

Next, as depicted in FIG. 9D, a TEOS film 242 is formed by the CVDmethod to be 100 nm in thickness on the entire upper surface of thesemiconductor substrate 110. Subsequently, a photoresist film 252 isformed on the TEOS film 242. This photoresist film 252 is exposed tolight and developed, so that an opening 252 a having the diameter of 0.7μm is formed in a position aligned with the W plug 214. After that, theTEOS film 242 is etched by using the photoresist film 252 as a mask toform an opening 242 a in which the W plug 241 is exposed. After that,the photoresist film 252 is removed.

Next, a Ti film with the thickness of 20 nm and a TiN film with thethickness of 50 nm (both of which are unillustrated) are formed on theentire upper surface of the semiconductor substrate 110. Thereafter, W(tungsten) is deposited by the CVD method on the entire upper surface ofthe semiconductor substrate 110, so that a W film is formed on the TEOSfilm 242 and the openings 242 a are filled with W. After that, the Wfilm, the TiN film, and the Ti film which are on the TEOS film 242 areremoved by the CMP method. With this, as depicted in FIG. 9E, the headportion of the W plug 241 is formed and the shape of the W plug 241becomes a rivet-like shape. After that, the plasma annealing isperformed in an atmosphere containing nitrogen and oxygen at thetemperature of 350° C. for 2 minutes.

Next, as depicted in FIG. 9F, a SiON film 125 is formed by the plasmaCVD method to be 100 nm in thickness on the entire upper surface of thesemiconductor substrate 110. Subsequently, a TEOS film 126 is formed bythe CVD method to be 100 nm in thickness on the SiON film 125. Then, adewatering process is performed by heating under conditions of the flowrate of nitrogen being 2 litters per minute and the temperature of 650°C. for 30 minutes. Thereafter, a hydrogen barrier film 127 made ofaluminum oxide (for example, Al₂O₃) is formed by the PVD method on theTEOS film 126. The processes thereafter are the same as those of thefirst embodiment, and the description thereof is omitted here.

(Third Manufacturing Method)

FIGS. 10A to 10F are cross-sectional views depicting a third method formanufacturing a semiconductor device according to the present embodimentin the order of processes. Note that, in place of the TEOS film 242, aninsulating film made of SiON, SiN, or aluminum oxide is formed here.

Firstly, by a method similar to that of the first embodiment, asdepicted in FIG. 10A, formed on and in a semiconductor substrate 110 arean element isolation film 111, a p-well 112, a gate electrode 114, a lowconcentration impurity region 116, a sidewall 117, a high concentrationimpurity region 118, a stopper layer 120, a first interlayer insulatingfilm 121, and the like. After that, a SiON film as an etching stopperfilm 122 is formed by the CVD method to be 100 nm in thickness on theinterlayer insulating film 121.

Subsequently, as depicted in FIG. 10B, a photoresist film 261 is formedon the etching stopper film 122. This photoresist film 261 is exposed tolight and developed to form an opening 261 a having the diameter of 0.55μm in a predetermined region. After that, the etching is performed byusing this photoresist film 261 as a mask to form a contact hole 121 aextending from the upper surface of the etching stopper film 122 andreaching the high concentration impurity region 118. Here, formed arenot only the contact hole 121 a extending from the upper surface of theetching stopper film 122 and reaching the high concentration impurityregion 118 but also the contact hole 121 a extending from the uppersurface of the etching stopper film 122 and reaching the gate electrode(silicon wiring) 114 on the element isolation film 111 in the peripheralcircuit forming region.

Next, after the photoresist film 261 is removed, a Ti film with thethickness of 20 nm and a TiN film with the thickness of 50 nm (both ofwhich are unillustrated) are formed by, for example, the PVD method onthe entire upper surface of the semiconductor substrate 110. Then, thewall surface of the contact hole 121 a is covered with these Ti film andTiN film. Thereafter, W (tungsten) is deposited by, for example, the CVDmethod on the entire upper surface of the semiconductor substrate 110,so that a W film is formed on the etching stopper film 122 and thecontact hole 121 a is filled with W. After that, the W film, the TiNfilm, and the Ti film which are on the etching stopper film 122 areremoved by the CMP method. With this, as depicted in FIG. 10C, a W plug241 (however, the head portion is excluded) is formed by filling thecontact hole 121 a with W.

Next, a TiN film (unillustrated) is formed by, for example, the PVDmethod to be 50 nm in thickness on the entire upper surface of thesemiconductor substrate 110. Subsequently, as depicted in FIG. 10D, a W(tungsten) film 262 is formed by, for example, the CVD method to be 200nm in thickness on the entire upper surface of the semiconductorsubstrate 110. Thereafter, a photoresist is applied onto the W film 262and is exposed to light and developed to form a photoresist film 263covering a predetermined region on the W film 262. This photoresist film263 is formed, above the W plug 241, to have the diameter of 0.7 μm insize.

Next, the W film 262 is etched by using the photoresist film 263 as amask. With this, as depicted in FIG. 10E, the head portion of the W plug241 is formed and the shape of the W plug becomes a rivet-like shape.After that, the photoresist film 263 is removed.

Next, an insulating film 264 for preventing the W plug from beingoxidized is formed on the entire upper surface of the semiconductorsubstrate 110. The insulating film 264 is formed of SiON, SiN, oraluminum oxide (such as Al₂O₃). Here, the insulating film 264 isdesigned to be formed of aluminum oxide. The insulating film 264 isformed on the entire upper surface of the semiconductor substrate 110,and, thereafter, the insulating film 264 is polished until the W plug241 is exposed, and thus the surface thereof is planarized.

Next, as depicted in FIG. 10F, a SiON film 125 is formed by the plasmaCVD method to be 100 nm in thickness on the entire upper surface of thesemiconductor substrate 110. Subsequently, a TEOS film 126 is formed bythe CVD method to be 100 nm in thickness on the SiON film 125. Then, thedewatering process is performed by heating under conditions of the flowrate of nitrogen being 2 litters per minute and the temperature of 650°C. for 30 minutes. Thereafter, a hydrogen barrier film 127 made ofaluminum oxide (for example, Al₂O₃) is formed by the PVD method on theTEOS film 126. The processes thereafter are the same as those of thefirst embodiment, and the description thereof is omitted here.

(Fifth Embodiment)

FIG. 11 is a schematic view depicting the structure of a semiconductordevice according to a fifth embodiment. The present embodiment isdifferent from the fourth embodiment in that a SiON film 217 is formedon an etching stopper film 122. Other components are basically the sameas those of the fourth embodiment. Accordingly, in FIG. 11, the samereference numerals are given to denote the components same as those inFIG. 7, and the detailed description thereof is omitted.

In the present embodiment, after an etching stopper film 122 is formed,a SiON film 271 is formed on the etching stopper film 122. Thereafter,the SiON film 271 is processed by the photolithography method and theetching method to form, in a predetermined region, an opening in whichthe etching stopper film 122 is exposed. After that, thephotolithography method and the etching method are used to form acontact hole extending from the upper surface of the etching stopperfilm 122 exposed in the opening and reaching a high concentrationimpurity region 118.

Subsequently, a TiN film and a Ti film are formed on the entire uppersurface of the semiconductor substrate 110 and the wall surface of thecontact hole is covered with these TiN film and Ti film. Thereafter, W(tungsten) is deposited on the entire upper surface of the semiconductorsubstrate 110 and the contact hole is filled with W. After that,polishing is performed by the CMP method until the SiON film 271 isexposed. In this manner, formed is a W plug 241 in a rivet shape withthe upper portion thereof wide.

The processes thereafter are the same as those of the fourth embodiment,and the description thereof is omitted here. In the present embodiment,effects similar to those of the fourth embodiment can be also obtained.

Note that the semiconductor device according to the present embodimentcan be manufactured by the second manufacturing method or the thirdmanufacturing method described in the fourth embodiment.

(Sixth Embodiment)

FIG. 12 is a schematic view depicting the structure of a semiconductordevice according to a sixth embodiment. The present embodiment isdifferent from the first embodiment in that an etching stopper film isdisposed on an upper side of a ferroelectric capacitor 131. Othercomponents are basically the same as those of the first embodiment.Accordingly, in FIG. 12, the same reference numerals are given to denotethe components same as those in FIG. 3, and the detailed descriptionthereof is omitted.

As depicted in FIG. 12, in the present embodiment, a method similar tothat of the first embodiment is used to form, on and in a semiconductorsubstrate 110, an element isolation film 111, a transistor T, a stopperlayer 120, and a first interlayer insulating film 121. After that, theupper surface of the interlayer insulating film 121 is planarized by theCMP method, and, thereafter, a TEOS film 126 and a hydrogen barrier film127 are formed.

Subsequently, formed on the hydrogen barrier film 127 is a ferroelectriccapacitor 131 constituted of a lower electrode 128 a, a ferroelectricfilm 129, and an upper electrode 130 a. Thereafter, if needed, analuminum oxide (Al₂O₃) film (unillustrated) is formed on the entireupper surface of the semiconductor substrate 110, so that theferroelectric capacitor 131 is covered with the aluminum oxide film.

Thereafter, an interlayer insulating film 311 made of TEOS-NSG is formedon the entire upper surface of the semiconductor substrate 110. Afterthat, the surface of the interlayer insulating film 311 is polished andplanarized by the CMP method. Then, an etching stopper film 312 made ofSiON is formed on this interlayer insulating film 311 to be, forexample, 100 nm in thickness.

Next, a photoresist film is formed on the etching stopper film 312.Then, this photoresist film is exposed to light and developed to form anopening in a predetermined position. After that, the etching isperformed by using this photoresist film as a mask to form a contacthole extending from the upper surface of the etching stopper film 312and reaching the high concentration impurity region 118. Subsequently,the wall surface of this contact hole is covered with a Ti film and aTiN film, and the contact hole is filled with W (tungsten) to form aplug 313 to be electrically connected to the high concentration impurityregion 118. After that, an interlayer insulating film 314 made ofTEOS-NSG is formed on the etching stopper film 312 by the plasma CVDmethod.

Next, the photolithography method and the etching method are used toform a contact hole extending from the upper surface of the interlayerinsulating film 314 and reaching the plug 313. Then, the contact hole isfilled with W (tungsten) to form a plug 315 to be electrically connectedto the plug 313. After that, a TiN film (unillustrated) is formed as abarrier metal on the entire upper surface of the substrate 110.

Next, the photolithography method and the etching method are used toform a contact hole extending from the upper surface of the interlayerinsulating film 314 and reaching the upper electrode 130 a of theferroelectric capacitor 131, and a contact hole extending from the uppersurface of the interlayer insulating film 314 and reaching the lowerelectrode 128 a of the ferroelectric capacitor 131. Thereafter, analuminum (aluminum alloy) film is formed on the entire upper surface ofthe semiconductor substrate 110 and aluminum is filled in the contactholes. Then, by the photolithography method and the etching method, thealuminum film is patterned to form a wiring 138 of a first wiring layer.

The processes thereafter are the same as those of the first embodiment,and the description thereof is omitted here. In the present embodiment,effects similar to those of the first embodiment can be also obtained.

FIG. 13 is a schematic view depicting a modified example of the sixthembodiment. As depicted in this FIG. 13, an oxide film with a thicknessof 50 to 100 nm may be formed as a cap layer 351 under the etchingstopper film 312. When the interlayer insulating film 311 formed on theferroelectric capacitor 131 is polished by the CMP method, a void(space) is generated in the interlayer insulating film 311. This maycause moisture or hydrogen to penetrate into the space, and thus causethe characteristic of the ferroelectric capacitor 131 to bedeteriorated. As depicted in FIG. 13, the cap layer 351 is formed on theinterlayer insulating film 311 to fill the void, and, thereafter, theetching stopper film 312 is formed. As a result, the characteristic ofthe ferroelectric capacitor 131 can be more securely prevented frombeing deteriorated.

In addition, a hydrogen barrier film (unillustrated) may be formed abovethe etching stopper film 312. With this, the penetration of moisture andhydrogen into the ferroelectric capacitor 131 can be further securelyprevented. Thus, the characteristic of the ferroelectric capacitor 131can be more securely prevented from being deteriorated.

(Seventh Embodiment)

FIG. 14 is a schematic view depicting the structure of a semiconductordevice according to a seventh embodiment. The present embodiment isdifferent from the sixth embodiment in that a TEOS (silicon oxide) film321 is formed on an etching stopper film 312. Other components arebasically the same as those of the sixth embodiment. Accordingly, inFIG. 14, the same reference numerals are given to denote the componentssame as those in FIG. 12, and the detailed description thereof isomitted.

In the present embodiment, after an etching stopper film 312 is formed,a TEOS film 321 is formed by the CVD method to be, for example, 100 nmin thickness on the etching stopper film 312. Subsequently, by thephotolithography method and the etching method, formed is a contact holeextending from the upper surface of the TEOS film 321 and reaching ahigh concentration impurity region 118. Then, this contact hole isfilled with W (tungsten) to form a plug 313.

Thereafter, an interlayer insulating film 314 made of TEOS-NSG is formedby the plasma CVD method on the entire upper surface of a semiconductorsubstrate 110. After that, the photolithography method and the etchingmethod are used to form a contact hole extending from the upper surfaceof the interlayer insulating film 314 and reaching the plug 313. Then,this contact hole is filled with W (tungsten) to form a plug 315 whichis electrically connected to the plug 313.

Subsequently, by the photolithography method and the etching method,formed are a contact hole extending from the upper surface of theinterlayer insulating film 314 and reaching an upper electrode 130 a ofa ferroelectric capacitor 131 and a contact hole extending from theupper surface of the interlayer insulating film 314 and reaching a lowerelectrode 128 a of the ferroelectric capacitor 131. Thereafter, analuminum (aluminum alloy) film is formed on the entire upper surface ofthe semiconductor substrate 110 and aluminum is filled into the contactholes. Then, by the photolithography method and the etching method, thealuminum film is patterned to form a wiring 138 of a first wiring layer.

The processes thereafter are the same as those of the first embodiment,and the description thereof is omitted here. In the present embodiment,effects similar to those of the first embodiment can be also obtained.

FIG. 15 is a schematic view depicting a modified example of the seventhembodiment. As depicted in this FIG. 15, an oxide film with thethickness of 50 to 100 nm may be formed as a cap layer 351 under theetching stopper film 312. With this, a void which is generated in theinterlayer insulating film 311 at the time of the CMP processing can befilled. Accordingly, the characteristic of the ferroelectric capacitor131 can be more securely prevented from being deteriorated.

In addition, a hydrogen barrier film (unillustrated) may be formed abovethe etching stopper film 312. With this, the penetration of moisture andhydrogen into the ferroelectric capacitor 131 can be further securelyprevented. Thus, the characteristic of the ferroelectric capacitor 131can be more securely prevented from being deteriorated.

(Eighth Embodiment)

FIG. 16 is a schematic view depicting the structure of a semiconductordevice according to an eighth embodiment. The present embodiment isdifferent from the sixth embodiment in that a moisture barrier film 322made of SiON is formed on an etching stopper film 312. Other componentsare basically the same as those of the sixth embodiment. Accordingly, inFIG. 16, the same reference numerals are given to denote the componentssame as those in FIG. 12, and the detailed description thereof isomitted.

In the present embodiment, after an etching stopper film 312 and a Wplug 313 are formed, a SiON film 322 is formed by the plasma CVD methodto be, for example, 100 nm in thickness on the etching stopper film 312.After that, an interlayer insulating film 314 made of TEOS-NSG is formedon the SiON film 322 by the plasma CVD method.

After that, the photolithography method and the etching method are usedto form a contact hole extending from the upper surface of theinterlayer insulating film 314 and reaching the plug 313. Then, thiscontact hole is filled with W (tungsten) to form a plug 315 which iselectrically connected to the plug 313. Thereafter, a TiN film(unillustrated) is formed as a barrier metal on the entire upper surfaceof the substrate 110.

Subsequently, by the photolithography method and the etching method,formed are a contact hole extending from the upper surface of theinterlayer insulating film 314 and reaching an upper electrode 130 a ofa ferroelectric capacitor 131 and a contact hole extending from theupper surface of the interlayer insulating film 314 and reaching a lowerelectrode 128 a of the ferroelectric capacitor 131. Thereafter, analuminum (aluminum alloy) film is formed on the entire upper surface ofthe semiconductor substrate 110 and aluminum is filled into the contactholes. Then, by the photolithography method and the etching method, thealuminum film is patterned to form a wiring 138 of a first wiring layer.

The processes thereafter are the same as those of the first embodiment,and the description thereof is omitted here. In the present embodiment,effects similar to those of the first embodiment can be also obtained.

FIG. 17 is a schematic view depicting a modified example of the eighthembodiment. As depicted in this FIG. 17, an oxide film with thethickness of 50 to 100 nm may be formed as a cap layer 351 under theetching stopper film 312. With this, a void which is generated in theinterlayer insulating film 311 at the time of the CMP processing can befilled. Accordingly, the characteristic of the ferroelectric capacitor131 can be more securely prevented from being deteriorated.

In addition, a hydrogen barrier film (unillustrated) may be formed abovethe etching stopper film 312. With this, the penetration of moisture andhydrogen into the ferroelectric capacitor 131 can be further securelyprevented. Thus, the characteristic of the ferroelectric capacitor 131can be more securely prevented from being deteriorated.

(Ninth Embodiment)

FIG. 18 is a schematic view depicting the structure of a semiconductordevice according to a ninth embodiment. The present embodiment isdifferent from the sixth embodiment in the shape of the cross section ofa plug to be connected to a high concentration impurity region 118.Other components are basically the same as those of the sixthembodiment. Accordingly, in FIG. 18, the same reference numerals aregiven to denote the components same as those in FIG. 12, and thedetailed description thereof is omitted.

In the present embodiment, after an etching stopper film 312 is formed,a TEOS film 331 is formed on the etching stopper film 312. Then, anopening is formed in the TEOS film 311 by using a method depicted in,for example, FIGS. 8B to 8D. Thereafter, a contact hole extending fromthe upper surface of the etching stopper film 312 exposed inside theopening and reaching the high concentration impurity region 118 isformed, and the contact hole is filled with W (tungsten). In thismanner, a rivet-like W plug 332 with a diameter in an upper portionbeing larger than those in other portions is formed.

Thereafter, an interlayer insulating film 314 made of TEOS-NSG is formedby the plasma CVD method on the TEOS film 331. After that, a contacthole extending from the upper surface of this interlayer insulating film314 and reaching the plug 332 is formed. Then, this contact hole isfilled with W (tungsten) to form a plug 315 which is electricallyconnected to the plug 332.

Subsequently, by the photolithography method and the etching method,formed are a contact hole extending from the upper surface of theinterlayer insulating film 314 and reaching an upper electrode 130 a ofa ferroelectric capacitor 131 and a contact hole extending from theupper surface of the interlayer insulating film 314 and reaching a lowerelectrode 128 a of the ferroelectric capacitor 131. Thereafter, analuminum (aluminum alloy) film is formed on the entire upper surface ofa semiconductor substrate 110 and aluminum is filled into the contactholes. Then, by the photolithography method and the etching method, thealuminum film is patterned to form a wiring 138 of a first wiring layer.

The processes thereafter are the same as those of the first embodiment,and the description thereof is omitted here. In the present embodiment,effects similar to those of the first embodiment can be also obtained.Note that the rivet-like W plug 332 may be formed by the secondmanufacturing method or the third manufacturing method described in thefourth embodiment.

FIG. 19 is a schematic view depicting a modified example of the ninthembodiment. As depicted in this FIG. 19, an oxide film with thethickness of 50 to 100 nm may be formed as a cap layer 351 under theetching stopper film 312. With this, a void which is generated in theinterlayer insulating film 311 at the time of the CMP processing can befilled. Accordingly, the characteristic of the ferroelectric capacitor131 can be more securely prevented from being deteriorated.

In addition, a hydrogen barrier film (unillustrated) may be formed abovethe etching stopper film 312. With this, the penetration of moisture andhydrogen into the ferroelectric capacitor 131 can be further securelyprevented. Thus, the characteristic of the ferroelectric capacitor 131can be more securely prevented from being deteriorated.

(Tenth Embodiment)

FIG. 20 is a schematic view depicting the structure of a semiconductordevice according to a tenth embodiment. The present embodiment isdifferent from the ninth embodiment in that a SiON film 341 is formed onan etching stopper film 312. Other components are basically the same asthose of the ninth embodiment. Accordingly, in FIG. 20, the samereference numerals are given to denote the components same as those inFIG. 18, and the detailed description thereof is omitted.

In the present embodiment, after an etching stopper film 312 is formed,a SiON film 341 is formed on the etching stopper film 312. Subsequently,this SiON film 341 is processed by the photolithography method and theetching method to form, in a predetermined region, an opening in whichthe etching stopper film 312 is exposed. Thereafter, by thephotolithography method and the etching method, formed is a contact holeextending from the upper surface of the etching stopper film 312 exposedin the opening and reaching a high concentration impurity region 118.Then, this contact hole is filled with W (tungsten) to form a rivet-likeW plug 332 with a diameter in an upper portion being larger than thosein other portions.

Thereafter, an interlayer insulating film 314 made of TEOS-NSG is formedby the plasma CVD method on the SiON film 341. After that, a contacthole extending from the upper surface of the interlayer insulating film314 and reaching a plug 332 is formed. Then, this contact hole is filledwith W (tungsten) to form a plug 315 which is electrically connected tothe plug 332.

Subsequently, by the photolithography method and the etching method,formed are a contact hole extending from the upper surface of theinterlayer insulating film 314 and reaching an upper electrode 130 a ofa ferroelectric capacitor 131 and a contact hole extending from theupper surface of the interlayer insulating film 314 and reaching a lowerelectrode 128 a of the ferroelectric capacitor 131. Thereafter, analuminum (aluminum alloy) film is formed on the entire upper surface ofa semiconductor substrate 110 and aluminum is filled into the contactholes. Then, by the photolithography method and the etching method, thealuminum film is patterned to form a wiring 138 of a first wiring layer.

The processes thereafter are the same as those of the first embodiment,and the description thereof is omitted here. In the present embodiment,effects similar to those of the first embodiment can be also obtained.

FIG. 21 is a schematic view depicting a modified example of the tenthembodiment. As depicted in this FIG. 21, an oxide film with thethickness of 50 to 100 nm may be formed as a cap layer 351 under theetching stopper film 312. With this, a void which is generated in theinterlayer insulating film 311 at the time of the CMP processing can befilled. Accordingly, the characteristic of the ferroelectric capacitor131 can be more securely prevented from being deteriorated.

In addition, a hydrogen barrier film (unillustrated) may be formed abovethe etching stopper film 312. With this, the penetration of moisture andhydrogen into the ferroelectric capacitor 131 can be further securelyprevented. Thus, the characteristic of the ferroelectric capacitor 131can be more securely prevented from being deteriorated.

(Other Embodiments)

In all of the above-described embodiments, it is assumed that there isno process to cut a hydrogen barrier film (hydrogen barrier films 127and 134), a SiON film (SiON films 125, 135, 221, 271, 322, and 341), andan etching stopper film (etching stopper films 122 and 312) and thesefilms are formed on the entire upper surface of a semiconductorsubstrate. However, as depicted in FIG. 22, these films may be disposedon a part of the semiconductor substrate. FIG. 22 is a top viewdepicting a chip forming region 410 for one chip of the semiconductorsubstrate, and 411 denotes a memory cell forming region, 412 denotes aperipheral circuit region, and 413 denotes a terminal forming region.This FIG. 22 depicts an example in which a hydrogen barrier film, a SiONfilm, and an etching stopper film are formed only in the hatched portionin the figure, that is, in the memory cell forming region 411.

In addition, as depicted in FIG. 23, a hydrogen barrier film, a SiONfilm, and an etching stopper film may be excluded from a scribe region320. That is, after these films are formed on the entire upper surfaceof a semiconductor substrate by the CVD method or the like, the films inthe scribe region 320 may be removed by etching.

In addition, in all of the above-described embodiments, the descriptionis given of a case where the present invention is applied to a FeRAMhaving a planer-type ferroelectric capacitor. However, as a matter ofcourse, the present invention can be applied to a FeRAM having astack-type capacitor.

All examples and conditional language recited herein are intended forpedagogical purposes to aid the reader in understanding the inventionand the concepts contributed by the inventor to furthering the art, andare to be construed as being without limitation to such specificallyrecited examples and conditions, nor does the organization of suchexamples in the specification relate to a showing of the superiority andinferiority of the invention. Although the embodiments of the presentinventions have been described in detail, it should be understood thatthe various changes, substitutions, and alterations could be made heretowithout departing from the spirit and scope of the invention.

1. A semiconductor device comprising: a semiconductor substrate; atransistor formed in the semiconductor substrate; a first insulatingfilm formed on the semiconductor substrate to cover the transistor; anetching stopper film formed on the first insulating film; a first plugformed by filling a conductive material into a contact hole extendingfrom an upper surface of the etching stopper film and reaching animpurity region constituting the transistor; a SiON film formed on theetching stopper film; a hydrogen barrier film formed over the SiON film;a ferroelectric capacitor formed on the hydrogen barrier film; a secondinsulating film formed on the hydrogen barrier film to cover theferroelectric capacitor; and a second plug formed by filling aconductive material into a contact hole extending from an upper surfaceof the second insulating film and reaching the first plug.
 2. Thesemiconductor device according to claim 1, wherein a metal silicidelayer is formed on the impurity region.
 3. The semiconductor deviceaccording to claim 1, wherein the metal silicide layer is selected fromcobalt silicide or titanium silicide.
 4. The semiconductor deviceaccording to claim 1, wherein the first plug reaches the metal silicidelayer.
 5. The semiconductor device according to claim 1, wherein theetching stopper film has a thickness of 20 nm to 150 nm.
 6. Thesemiconductor device according to claim 5, wherein the etching stopperfilm is formed of silicon oxynitride or silicon nitride.
 7. Thesemiconductor device according to claim 1, wherein the etching stopperfilm is formed of a metal oxide.
 8. The semiconductor device accordingto claim 7, wherein the etching stopper film has a thickness equal to orless than 100 nm.
 9. The semiconductor device according to claim 1,wherein the ferroelectric capacitor has a lower electrode, aferroelectric film and an upper electrode comprised of a first andsecond IrO₂ film stack.